Assessing the impact of structured real-time design methods

Computer systems in today's society require an increasing amount of embedded real-time software and hardware systems. Their application has introduced new problems for the software engineer related to the complexity of such systems. The early stages of the software development process are vital for the successful implementation of computer systems. Three structured design methods for real-time software systems that are common in industrial projects are compared (SCR, RTSA, DARTS). This comparison is based on the application of all methods to the specification of a commercial heating system which is in the area of 200 function points (6 person-months development time). The complete development process is supported by a heterogeneous CASE environment for reproducibility and hence better comparability. High-order Petri nets are introduced as a graphic formalism for both analysis and architectural design of concurrent systems. The methods are compared quantitatively providing different complexity metrics over time and qualitatively by subjective observations from this and other projects. In the given projects DARTS has some advantages compared to the other methods.